Satellites and other space vehicles normally include an array of solar cells that convert solar energy to electrical energy and provide the primary source of power for operating the various onboard electrical loads. Rechargeable batteries are provided as a secondary source of electrical power when solar energy is not available or is insufficient. It is desirable to periodically recondition the batteries through a process that involves fully discharging and recharging the batteries.
In one prior art reconditioning system, see for example Newell et al 3,997,830, a plurality of batteries is provided and each battery is reconditioned in sequence so that part of the total secondary energy storage capability is always maintained on line for power demands that might occur during the reconditioning process. The individual cells of a battery are discharged simultaneously by connecting resistors across the cells. The terminal voltage of the battery being reconditioned is monitored and when a predetermined low level is reached the battery is connected to the solar array through battery charging circuitry and recharged. The additional battery or batteries and associated charge and discharge electronics represents a significant weight and cost penalty.
The battery is also an emergency source of high current to clear faults that may occur on the spacecraft. It is desirable that this capability be available during the reconditioning process. Where a plurality of batteries is available this requirement is readily met, however the weight and cost tradeoff may be prohibitive.